Yes the compression was lowered in 72 and the valve size went from 2.02 to 1.88s. 2.02s will move more air at the top end, They will not add low end torque and some will actually tell you the bigger valve will hurt low end throttle response.
They also switched to a different passenger side exhaust manifolds in 71 as well as switching to the Thermoquad. Neither of which makes a difference in this case either.
His problem is a big pile of mis-match parts.
